This application claims the priority of German Patent Document 100 48 846.3, filed in Germany, Oct. 2, 2000, the disclosure of which is expressly incorporated by reference herein.
The present invention relates to an extendible solar generator with an extendible support array structure which can be used, for example, in the case of spacecraft but can also be used in other fields independently of applications in space operations technology.
An extendible support array structure is known, for example, from European Patent Document EP 0 858 946, in which a mast is described which consists of individual struts connected with one another in a scissors-type manner. From German Patent Document DE 2 110 626, extendible solar generators are known which are extended by means of telescopic rods or struts made of individual elements which are flexibly connected with one another at their ends. Solar generators are also described there which have struts which are formed by the rolling-off of a tape with internal tension (measuring tape effect). German Patent Document DE 32 23 839 describes a collapsible solar generator which is held by means of an unfurlable mast made of individual mast sections. In the case of these devices, an extendible solar cell structure is also extended as a result of the extending movement of the support array structure.
However, it is a disadvantage of this state of the art that a defined guided extension of the solar generator and particularly of the solar cell structure can take place only insufficiently, in which case there is also the danger of a damaging or even a jamming of the arrangement as a result of the mutual influencing of the extension movement of the support array structure and of the solar cell structure when the two structures are extended simultaneously.
It is therefore an object of the present invention to provide an extendible solar generator with an extendible array structure which ensures a reliable and defined rolling-out.
This object is achieved according to preferred embodiments of the invention by providing an extendible solar generator having an extendible solar cell structure, and an extendible support array structure which has a first cross member and is connected with a stowage housing for the solar cell structure, wherein the support array structure can be extended independently of the solar cell structure and has guiding devices for extending the solar cell structure after the extension of the support array structure has taken place.
An object of the present invention is an extendible solar generator with an extendible solar cell structure and an extendible support array structure with a first cross member, the support array structure being connected with a stowage housing for the solar cell structure. Such extendible solar cell structures can, for example, be rolled up or folded together in order to require a stowage space which is as small as possible. The solar cell structures are usually accommodated in stowage housings in order to protect them from destruction or damaging influences before they are operated.
According to the invention, it is now provided that the support array structure can be extended independently of the solar cell structure and has guiding devices for extending the solar cell structure after the support array structure has been extended. As a result, the extension movement of the support array structure is uncoupled from the extension movement of the solar cell structure. Each of the two movements can now be optimized separately and, during the operation, can be carried out by the respective other extension movement, so that a disturbing mutual influencing of the extension movements and the participating components can be avoided. On the contrary, after its extension has taken place, the support array structure forms a stable holding and guiding device for the subsequently occurring extending movement of the solar cell structure. As a result, the extending of the support array structure can take place first, in which case the second cross member first can remain connected with the stowage housing. It is only after the extension of the support array structure that the second cross member moves along the support array structure and takes along the solar cell structure connected with it.
For this purpose, it can particularly be provided according to certain preferred embodiments of the invention that a second cross member, which is connected with the solar cell structure and is longitudinally movably arranged with respect to the support array structure, and first guiding cables are provided as guiding devices, the first cross member and the second cross member being connected at their ends by the first guiding cables. The second cross member provides an advantageous stabilization of the free movable end of the solar cell structure and the punctually high forces transmitted by the guiding cables do not act directly upon the solar cell structure but, on the contrary, upon the more stable cross member, whereby the danger of damage to the solar cell structure by the extension movement is reduced.
In order to ensure a construction of the entire arrangement which is as compact and weight-reducing as possible, it may be provided according to certain preferred embodiments of the invention that the first cross member is constructed as part of a lid unit and the second cross members is constructed as an intermediate bottom of the stowage housing for the solar cell structure.
The stowage housing is preferably constructed according to certain preferred embodiments of the invention such that the part elements of the extendible support array structure in the closed condition of the stowage housing can be braced under prestress between the first cross member and the second cross member. This can take place, for example, by a corresponding design of the interior of the stowage housing, for example, just by its size. As a result, on the one hand, the extension movement of the support array structure during the opening of the stowage housing can be promoted by the then released prestress; on the other hand, for example, also reversibly deformable part elements for the support array structure may be provided which can then be deformed with respect to their height, whereby the required height of the stowage housing can be reduced.
In order to ensure a fixing of the solar cell structure which is as optimal as possible, particularly in the unfolded or extended condition, it may be provided that the flexible solar cell structure is connected with guiding cables which can be mounted between the second cross member and the stowage housing.
As described above, the flexible solar cell structure can be rolled up or folded before the mounting or can generally be arranged above one another in several layers. In order to protect the surface of the solar cell structure and compensate possible tolerances between the individual layers, it may be provided according to certain preferred embodiments of the invention that elastic separating foils are arranged between the individual layers.
The extendible support array structure may consist of several mutually connected part elements according to certain preferred embodiments of the invention which are reversibly deformable such that a change of the cross-sectional surface of the part elements can take place perpendicularly to their longitudinal dimension. Thus, the part elements can be compressed perpendicular to their longitudinal dimension by the effect of force or prestress, which reduces the require stowage volume of the part elements. When the effect of the force or prestress is eliminated again, the part elements will reversibly return to their original shape. On the other hand, the construction of the individual elements as part elements ensures a high stiffness of the individual elements as soon as the effect of the force or prestress was eliminated.
At their ends, the part elements are connected with one another by elastic elements according to certain preferred embodiments of the invention. As a result, the part elements can be stowed in the shape of an accordion, whereby a stack of individual part elements can be formed which rest upon one another perpendicular to the longitudinal dimension of the roll-out support array structure. Thus, a very compact stowage possibility is obtained for the individual part elements, in which case the stowage volume can be further reduced by the exercising of a corresponding force or prestress, as described above, by way of a deformation of the part elements. On the other hand, as a result of the suitable adjustment of the internal mechanical prestress of the elastic elements, it is achieved that, when the force or prestress is eliminated, an automatic unfolding of the support array structure can take place by this prestressing of the mechanical elements and thus an extension of the structure. The internal prestressing of the elastic elements also ensures the stiffness of the structure in the extended condition.
In order to ensure a reversible deformability of the part elements according to certain preferred embodiments of the invention, it is necessary to design the part elements elastically. In this case, the part elements themselves may consist of an elastic material. However, it may also be provided that the part elements consist of part segments which extend in the longitudinal direction of the part elements and which, along surface lines of the part elements, are connected with one another by additional elastic elements or joints. Thus, the part elements may be constructed as tube elements or, for example, as semi-cylindrical parts of tubes. If elastic elements are provided, the individual part segments may have additional elasticity which, however, as a rule, may be designed to be less than the elasticity of the additional elastic elements. The elastic elements may be constructed, for example, as springs, such as leaf springs.
Basically, the part elements may also be arranged in a single row of mutually connected tube elements according to certain preferred embodiments of the invention, so that, in the extended condition, an individual support, such as, for example, an individual strut or an individual mast, is created. However, it may also be provided that at least a first part element is connected at a first end with a first end of a second part element, and at a second end, is connected with a second end of a third, fourth and fifth part element. As a result, two rows of part elements can be formed which are arranged parallel to one another, in which case, the rows are connected with one another and, in the extended condition, form a double support array structure, thus, for example, a double strut or a double mast. In the following, this will be abbreviated as double structure. As a result of such a measure, the stiffness of the support array structure can be further increased.
In principle, all suitable materials, particularly elastic materials, can be used for the tube elements. Thus, the tube elements may, for example, consist of a carbon fiber material. Such a material has the additional advantage of a lower weight while the stiffness is relatively high.
Other objects, advantages and novel features of the present invention will become apparent from the following detailed description of the invention when considered in conjunction with the accompanying drawings.